M17 (amateur radio)

[9] M17 uses Frequency-Division Multiple Access (FDMA) technology in which different communication streams are separated by frequency and run concurrently.

With a small hardware modification, TYT MD-380, MD-390 and MD-UV380 handheld transceivers can be flashed with a custom, free, open source firmware[12] to enable M17 support.

In July 2024, a US-based company Connect Systems, Inc. released the CS7000-M17, being the first commercial off-the-shelf handheld transceiver with native M17 support.

Modes bridged include DMR, P25, System Fusion, D-STAR, NXDN, AllStarLink, EchoLink and IRLP.

Kaczmarski, having experimented with TETRA and DMR, decided to create a completely non-proprietary protocol and named it after the club's street address - Mokotowska 17.

As every part of the protocol was intended to be open source, Codec 2, released under the GNU LGPL 2.1 license, was chosen as the speech encoder.

RF spectrum of the M17 protocol
Spectrogram of the M17 protocol transmission. Time is on vertical axis, advancing from bottom to top. There's a 40-millisecond preamble visible at the beginning of the transmission.
Prototype of the CS7000 M17 handheld radio (CS760)